Clamps



Aug. 20, 1957 M. A. GAMURA CLAMPS Filed Jilly 22,

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United States PatentO CLAMPS Michael A. Gamura, Detroit, Mich.

Application July 22, 1954, Serial N 0. 445,032

3 Claims. (Cl. 144290) This invention relates to improvements in adjustable hold down clamps for securing work pieces on tables of machines, angle plates and the like.

It is an object of the invention to provide an adjustable hold down clamp which is cheap and simple to manufacture and which includes a cross bar having a downturned portion at one extremity adapted to bear against a work piece, a leg depending from the other extremity provided with means for rapid vertical adjustment, and means for securing the bar upon a work table extending vertically through the said bar intermediately of the length of the latter; and wherein the securing means is also provided with means for rapid vertical adjustment so that the clamp may be quickly and easily adjusted to grip work pieces of different heights upon a work table.

Another object of the invention is to provide such a clamp wherein means are provided whereby the leg may be mounted for rapid vertical adjustment at either of two distances from the downturned portion of the bar so that if the available space on the table is relatively restricted the spacing of the leg from the said downturned portion may be reduced.

A further object of the invention is to provide such a clamp wherein the vertical distance from the cross bar to the bottom of the leg is adjustable, and wherein at no adjusted position of the leg does its upper extremity project above the top of the securing means for the bar so that the said leg cannot interfere with the operation of parts of the machine which extend over it and over the securing means.

Having thus briefly stated some of the objects and advantages of the invention I will now describe it in detail with the aid of the accompanying drawing, in which:

Figure l is a side elevation of the invention,

Figure 2 is a section on the line 2--2 of Figure 1, and

Figure 3 is a view similar to Figure 2 but with the coacting racks of the securing means for the cross bar disengaged for vertical adjustment relative to one another.

Figure 4 is an end view taken on the line 4-4 of Figure 1.

, Figure 5 is a detail showing one end of the clamp with the depending leg secured to the inner face of a block secured to the bar.

7 Figure 6 shows a slight modification wherein the lower extremity of the securing means is threaded for engagement with a plate or table.

Figure 7 is a detail showing a modification of the means for permitting release of the coacting racks from one another, and

Figure 8 is a similar detail of this modification but with the racks in engagement.

Referring to the drawing, 1 designates a cross bar having a vertical slot 2 therethrough intermediately of its length. Formed integral with the bar 1 at one extremity thereof is a downturned portion 3 adapted to engage the upper face of a work piece A and hold it immovable upon a work table B. Welded or otherwise suitably secured to the underside of the opposite extremity of the bar 1 and projecting slightly beyond that end thereof is a block 4 having vertical racks 5 and 5a on opposite sides thereof. The rack 5 is on the end of the block which projects beyond the end of the bar 1 to permit another rack 6 in engagement with it to be moved vertically past the adjacent extremity of the bar. Formed horizontally through the block 4 and its racks 5 and 5a is a tapped opening 7.

The securing means for the clamp includes a vertical rack 8 provided at its lower extremity with means for engagement with the work table B. In Figures 1, 2 and 3 the engaging means consists of a head 9 which is adapted to be inserted in a T-slot C in the table, and in the modified form shown in Figure 6 a threaded extremity 10 is provided on the lower end of the rack 8 which is adapted to be screwed into a tapped opening D in the work table B. 11 denotes a lock nut on the threaded extremity 10 for retaining the latter in firm engagement with the said tapped opening. Coacting with the rack 8 is another rack 12 from the upper extremity of which a stud 13 projects which passes through the slot 2 and has a nut 14 on its upper extremity which is tightened down upon a washer 15 resting upon the upper face. of the bar 1. Formed horizontally through the rack 8 is a tapped opening 16 to receive a screw 17 which also passes through a vertically elongated slot 18 formed through the rack 12 so that the said screw may retain the teeth of the racks 8 and 12 in engagement.

Formed on the rear face 19 of the rack 12 on the side of the latter remote from its teeth is a vertically elongated recess 20 which is wider than and in alignment with the slot 18. The inner portion 21 of the head of the screw 17 is substantially rectangular and relatively long and narrow, so that in one rotary position of the screw the said inner portion projects across the recess 20 and bears against opposite sides thereof to retain the teeth of the racks 8 and 12 in engagement. However when the screw 17 is turned to its position shown in Figure 3 the inner portion 21 of the head of the screw 17, being narrower than the recess 20, is adapted to enter the latter so that the racks may be moved sufficiently apart for the teeth of the tworacks to be disengaged. Then the racks are vertically adjustable relative to one another so that the vertical distance between the top of the stud 13 and the head may be adjusted. I

The rack 6 is integral with and forms the upper portion of a leg 22 the lower extremity of which is adapted to rest upon the work table B. Formed horizontally through the rack 6 is a vertically elongated slot 23 through which a screw 24 extends and is in threaded engagement with the tapped opening 7. Means similar to those above described are provided for rapid engagement or release of the racks 5 and 6 upon partial rotation of the screw 24 so that these racks may be readily secured to one another or as readily rendered vertically adjustable relative to one another.

The inner portion 27 of the head of the screw 24 is substantially rectangular and is relatively long and narrow. The side 25 of the rack 6 remote from its teeth, has an elongated recess 26 formed therethrough which is wider than the slot 23 and in vertical alignment with it. Moreover the width of the inner portion of the head of the screw 24 is slightly less than that of the recess 26. Consequently at one rotary position of the screw 24 the inner portion 27 of its head extends across the recess 26 and bears against the side 25 thereby retaining the teeth of the racks 5 and 6 in engagement, and at another rotary position of the screw the inner portion 27 of its head is adapted to enter the recess 26 at which time the racks 5 and 6 may be moved apart sufficiently for the teeth of one rack to disengage the teeth of the other. Then of course the racks 5 and 6 arever'tically movable relative to one another. When it is desired to engage the rack 6 a .3 with the rack a it is merely necessary to remove the screw 24 and reinsert it through the rack 6 after the latter has been placed in engagement with the rack 5a, as shown in Figure 5.

Figures 7 and 8 show a modification wherein a separate member 1911 rests against the rack 12a. In this instance the member 19:: is in the general form of a washer having a substantially oblong opening 20a therethrough, $80 that in one rotary position of the screw 17a the inner port10n 21a of the head of the latter which is again relatively long and narrow is adapted to enter the opening a. Then the racks 12a and 811 may be spaced sufficiently for their teeth to be disengaged. Then of course the two racks are vertically movable relative to one another. When the teeth of the two racks are again in engagement the inner portion 21a of the head of the screw 17a is .no longer in the opening 20a and therefore the screw 17a is again free to be turned so that the said inner portion bears against the outer face of the member 19a and then the two racks are secured in engagement with one another. From Figure 7 it will also be noted that the outer portion 21b of the head of the screw 17a is longer than the length of the opening 20a so that disengagement of the member 19a from the screw is prevented at all times.

While in the foregoing the preferred embodiments of the invention have been described and shown it is understood that further alterations and modifications may be made thereto provided the said alterations and modifications fall within the scope of the appended claims.

What I claim is:

1. An adjustable clamp comprising a bar having a work engaging portion at one extremity adapted to bear against the top of a workpiece and hold it immovable on a work table, a vertically extensible leg projecting downwardly from the opposite extremity of the bar adapted to bear upon the table, said bar being vertically apertured intermediately of its length, a vertical rack having means on its lower extremity for engaging the work table, a second vertical rack the teeth of which are adapted to engage the teeth of the first rack, a stud extending from the upper extremity of the second rack through the bar aperture, a nut on said stud for forcing the bar downward, one of the racks having a horizontal tapped opening extending therethrough transversely of its teeth, the other rack having a vertically elongated slot extending therethrough transversely of its teeth, a screw projecting through the elongated slot in threaded engagement with the tapped opening, the inner portion of the head of said screw being relatively long and narrow, the length of said inner portion being greater than the width or" said slot and the width of I said inner portion being less than that of the slot, whereby in one rotary position of the screw said inner portion is adapted to extend across the rear of the slotted rack to hold the teeth of the two racks in engagement and in another rotary position of the screw said is adapted to enter the slot and permit disengagement of the teeth of the two racks whereupon the racks may be longitudinally adjusted relative to one another, and the outer portion of the head of the screw being wider than the slot to prevent complete disengagement of the racks from one another.

2. An adjustable clamp comprising a bar having a work engaging portion at one extremity adapted to bear against the top of a workpiece and hold it immovable upon a work table, said bar being vertically apertured intermediately of its length, vertically extensible means having means on its lower extremity for engagement with the work table and a stud projecting from its upper exinner portion tremity through said aperture, a nut on said stud for exerting downward pressure on said bar, a vertical rack dependingly secured to the extremity of the bar remote from its work engaging portion, a second rack the teeth of which are adapted to engage the teeth of the first rack and having a leg projecting downwardly therefrom adapted to rest upon the table, one of the racks having a tapped opening extending horizontally therethrough transversely of its teeth, the other rack having a vertically elongated slot formed therethrough transversely of its teeth, a screw projecting through the elongated slot in threaded engagement with the tapped opening, the inner portion of the head of the screw being relatively long and narrow, the length of said inner portion being greater than the width of said slot and the width of said inner portion being less than that of the slot, whereby in one rotary position of the screw said inner portion is adapted to extend across the rear of the slotted rack and hold the teeth of the two racks in engagement and in another rotary position of the screw said inner portion is adapted to enter the slot and permit disengagement of the teeth of the two racks whereupon the racks may be longitudinally adjusted relative to one another, and the outer portion of the head of the screw being wider than the slot to prevent complete disengagement of the racks from one another.

3. An adjustable clamp comprising a bar having a work engaging portion at one extremity adapted to bear against the top of a workpiece and hold it immovable on a work table, a vertically extensible leg projecting downwardly from the opposite extremity of the bar adapted to bear upon the table, said bar being vertically apertured intermediately of its length, a vertical rack having means on its lower extremity for engaging the work table, a second vertical rack the teeth of which are adapted to engage the teeth of the first rack, a stud extending from the upper extremity of the second rack through the bar apertu're, a nut on said stud for forcing the bar downward, one of the racks having a horizontal tapped opening extending therethrough transversely of its teeth, the other rack having a vertically elongated slot extending therethrough transversely of its teeth, a screw projecting through the elongated slot in threaded engagement with the tapped opening, a washer on the screw of greater diameter than the width of the slot and interposed between the screw head and the slotted rack, said washer having a relatively long and narrow opening therethrough, the inner portion of the screw head being relatively long and narrow and adapted in one rotary position relative to the washer to extend through said opening to permit spacing the racks from one another and in another rotary position relative to the washer to bear against said washer and hold the teeth of the two racks in engagement, and the outer portion of the screw head being larger than the opening in said washer to prevent complete disengagement 0f the racks from one another.

References Cited in the file of this patent UNITED STATES PATENTS 456,877 Bingman July 28, 1891 1,072,363 Roberts Sept. 2, 1913 2,333,986 Crayton Nov. 9, 1943 2,374,263 Askin Apr. 24, 1945 2,639,744 Herbert May 26, 1953 FOREIGN PATENTS 385,568 Great Britain Dec. 29, 1932 591,087 Great Britain Aug. 6, 1947 

